原文:
C# 连蒙带骗不知所以然的搞定USB下位机读写
公司用了一台发卡机，usb接口，半双工，给了个dll，不支持线程操作，使得UI线程老卡。
懊恼了，想自己直接通过usb读写，各种百度，然后是无数的坑，最终搞定。
现将各种坑和我自己的某些猜想记录一下，也供各位参考。
一、常量定义
private const short INVALID_HANDLE_VALUE = -1;
private const uint GENERIC_READ = 0x80000000;
private const uint GENERIC_WRITE = 0x40000000;
private const uint FILE_SHARE_READ = 0x00000001;
private const uint FILE_SHARE_WRITE = 0x00000002;
private const uint CREATE_NEW = 1;
private const uint CREATE_ALWAYS = 2;
private const uint OPEN_EXISTING = 3;
private const uint FILE_FLAG_OVERLAPPED = 0x40000000;
private const uint FILE_ATTRIBUTE_NORMAL = 0x00000080;
主要用于CreateFile时用。
二、结构、枚举、类定义
private struct HID_ATTRIBUTES { public int Size; public ushort VendorID; public ushort ProductID; public ushort VersionNumber; } private struct SP_DEVICE_INTERFACE_DATA { public int cbSize; public Guid interfaceClassGuid; public int flags; public int reserved; } [StructLayout(LayoutKind.Sequential)] private class SP_DEVINFO_DATA { public int cbSize = Marshal.SizeOf<SP_DEVINFO_DATA>(); public Guid classGuid = Guid.Empty; public int devInst = 0; public int reserved = 0; } [StructLayout(LayoutKind.Sequential, Pack = 2)] private struct SP_DEVICE_INTERFACE_DETAIL_DATA { internal int cbSize; internal short devicePath; } private enum DIGCF { DIGCF_DEFAULT = 0x1, DIGCF_PRESENT = 0x2, DIGCF_ALLCLASSES = 0x4, DIGCF_PROFILE = 0x8, DIGCF_DEVICEINTERFACE = 0x10 } [StructLayout(LayoutKind.Sequential)] private struct HIDP_CAPS { /// <summary> /// Specifies a top-level collection's usage ID. /// </summary> public System.UInt16 Usage; /// <summary> /// Specifies the top-level collection's usage page. /// </summary> public System.UInt16 UsagePage; /// <summary> /// 输入报告的最大节数数量（如果使用报告ID，则包含报告ID的字节） /// Specifies the maximum size, in bytes, of all the input reports (including the report ID, if report IDs are used, which is prepended to the report data). /// </summary> public System.UInt16 InputReportByteLength; /// <summary> /// Specifies the maximum size, in bytes, of all the output reports (including the report ID, if report IDs are used, which is prepended to the report data). /// </summary> public System.UInt16 OutputReportByteLength; /// <summary> /// Specifies the maximum length, in bytes, of all the feature reports (including the report ID, if report IDs are used, which is prepended to the report data). /// </summary> public System.UInt16 FeatureReportByteLength; /// <summary> /// Reserved for internal system use. /// </summary> [MarshalAs(UnmanagedType.ByValArray, SizeConst = 17)] public System.UInt16[] Reserved; /// <summary> /// pecifies the number of HIDP_LINK_COLLECTION_NODE structures that are returned for this top-level collection by HidP_GetLinkCollectionNodes. /// </summary> public System.UInt16 NumberLinkCollectionNodes; /// <summary> /// Specifies the number of input HIDP_BUTTON_CAPS structures that HidP_GetButtonCaps returns. /// </summary> public System.UInt16 NumberInputButtonCaps; /// <summary> /// Specifies the number of input HIDP_VALUE_CAPS structures that HidP_GetValueCaps returns. /// </summary> public System.UInt16 NumberInputValueCaps; /// <summary> /// Specifies the number of data indices assigned to buttons and values in all input reports. /// </summary> public System.UInt16 NumberInputDataIndices; /// <summary> /// Specifies the number of output HIDP_BUTTON_CAPS structures that HidP_GetButtonCaps returns. /// </summary> public System.UInt16 NumberOutputButtonCaps; /// <summary> /// Specifies the number of output HIDP_VALUE_CAPS structures that HidP_GetValueCaps returns. /// </summary> public System.UInt16 NumberOutputValueCaps; /// <summary> /// Specifies the number of data indices assigned to buttons and values in all output reports. /// </summary> public System.UInt16 NumberOutputDataIndices; /// <summary> /// Specifies the total number of feature HIDP_BUTTONS_CAPS structures that HidP_GetButtonCaps returns. /// </summary> public System.UInt16 NumberFeatureButtonCaps; /// <summary> /// Specifies the total number of feature HIDP_VALUE_CAPS structures that HidP_GetValueCaps returns. /// </summary> public System.UInt16 NumberFeatureValueCaps; /// <summary> /// Specifies the number of data indices assigned to buttons and values in all feature reports. /// </summary> public System.UInt16 NumberFeatureDataIndices; }
都是从各种地方复制过来的。最后的结构注释从微软那里复制了英文，翻译了一句中文。因为这个坑最大。
三、Dll封装
/// <summary> /// 过滤设备，获取需要的设备 /// </summary> /// <param name="ClassGuid"></param> /// <param name="Enumerator"></param> /// <param name="HwndParent"></param> /// <param name="Flags"></param> /// <returns></returns> [DllImport("setupapi.dll", SetLastError = true)] private static extern IntPtr SetupDiGetClassDevs(ref Guid ClassGuid, uint Enumerator, IntPtr HwndParent, DIGCF Flags); /// <summary> /// 获取设备，true获取到 /// </summary> /// <param name="hDevInfo"></param> /// <param name="devInfo"></param> /// <param name="interfaceClassGuid"></param> /// <param name="memberIndex"></param> /// <param name="deviceInterfaceData"></param> /// <returns></returns> [DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern Boolean SetupDiEnumDeviceInterfaces(IntPtr hDevInfo, IntPtr devInfo, ref Guid interfaceClassGuid, UInt32 memberIndex, ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData); /// <summary> /// 获取接口的详细信息 必须调用两次 第1次返回长度 第2次获取数据 /// </summary> /// <param name="deviceInfoSet"></param> /// <param name="deviceInterfaceData"></param> /// <param name="deviceInterfaceDetailData"></param> /// <param name="deviceInterfaceDetailDataSize"></param> /// <param name="requiredSize"></param> /// <param name="deviceInfoData"></param> /// <returns></returns> [DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Auto)] private static extern bool SetupDiGetDeviceInterfaceDetail(IntPtr deviceInfoSet, ref SP_DEVICE_INTERFACE_DATA deviceInterfaceData, IntPtr deviceInterfaceDetailData, int deviceInterfaceDetailDataSize, ref int requiredSize, SP_DEVINFO_DATA deviceInfoData); /// <summary> /// 删除设备信息并释放内存 /// </summary> /// <param name="HIDInfoSet"></param> /// <returns></returns> [DllImport("setupapi.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern Boolean SetupDiDestroyDeviceInfoList(IntPtr HIDInfoSet); /// <summary> /// 获取设备文件 /// </summary> /// <param name="lpFileName"></param> /// <param name="dwDesiredAccess">access mode</param> /// <param name="dwShareMode">share mode</param> /// <param name="lpSecurityAttributes">SD</param> /// <param name="dwCreationDisposition">how to create</param> /// <param name="dwFlagsAndAttributes">file attributes</param> /// <param name="hTemplateFile">handle to template file</param> /// <returns></returns> [DllImport("kernel32.dll", SetLastError = true)] private static extern IntPtr CreateFile(string lpFileName, uint dwDesiredAccess, uint dwShareMode, uint lpSecurityAttributes, uint dwCreationDisposition, uint dwFlagsAndAttributes, uint hTemplateFile); [DllImport("kernel32.dll", SetLastError = true)] [return: System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.Bool)] private static extern bool WriteFile(System.IntPtr hFile, byte[] lpBuffer, uint nNumberOfBytesToWrite, out uint lpNumberOfBytesWritten, IntPtr lpOverlapped); [DllImport("kernel32.dll", SetLastError = true)] private static extern int CloseHandle(int hObject); /// <summary> /// 获得GUID /// </summary> /// <param name="HidGuid"></param> [DllImport("hid.dll")] private static extern void HidD_GetHidGuid(ref Guid HidGuid); [DllImport("hid.dll")] private static extern Boolean HidD_GetPreparsedData(IntPtr hidDeviceObject, out IntPtr PreparsedData); [DllImport("hid.dll")] private static extern uint HidP_GetCaps(IntPtr PreparsedData, out HIDP_CAPS Capabilities); [DllImport("hid.dll")] private static extern Boolean HidD_FreePreparsedData(IntPtr PreparsedData); [DllImport("hid.dll")] private static extern Boolean HidD_GetAttributes(IntPtr hidDevice, out HID_ATTRIBUTES attributes);
四、几个属性
private int _InputBufferSize; private int _OutputBufferSize; private FileStream _UsbFileStream = null;
五、几个方法
Usb设备的读写跟磁盘文件的读写没区别，需要打开文件、读文件、写文件，最后关闭文件。
磁盘文件大家都清楚，比如“c:\data\hello.txt”就是个文件名，前面加“\\计算机A”则是其他计算机上的某文件名，Usb设备也有文件名，如我的设备的文件名就是“\\?\hid#vid_5131&pid_2007#7&252e9bc9&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}”。
哪弄来的？头大了吧，我也头大，什么鬼？百度了，未果，所以干脆不管了。先来一个列出全部Usb设备文件名的方法
（一）获取所有Usb设备文件名
/// <summary> /// 获取所有Usb设备文件名 /// </summary> /// <returns></returns> public static List<string> GetUsbFileNames() { List<string> items = new List<string>(); //通过一个空的GUID来获取HID的全局GUID。 Guid hidGuid = Guid.Empty; HidD_GetHidGuid(ref hidGuid); //通过获取到的HID全局GUID来获取包含所有HID接口信息集合的句柄。 IntPtr hidInfoSet = SetupDiGetClassDevs(ref hidGuid, 0, IntPtr.Zero, DIGCF.DIGCF_PRESENT | DIGCF.DIGCF_DEVICEINTERFACE); //获取接口信息。 if (hidInfoSet != IntPtr.Zero) { SP_DEVICE_INTERFACE_DATA interfaceInfo = new SP_DEVICE_INTERFACE_DATA(); interfaceInfo.cbSize = Marshal.SizeOf(interfaceInfo); uint index = 0; //检测集合的每个接口 while (SetupDiEnumDeviceInterfaces(hidInfoSet, IntPtr.Zero, ref hidGuid, index, ref interfaceInfo)) { int bufferSize = 0; //获取接口详细信息；第一次读取错误，但可取得信息缓冲区的大小 SP_DEVINFO_DATA strtInterfaceData = new SP_DEVINFO_DATA(); var result = SetupDiGetDeviceInterfaceDetail(hidInfoSet, ref interfaceInfo, IntPtr.Zero, 0, ref bufferSize, null); //第二次调用传递返回值，调用即可成功 IntPtr detailDataBuffer = Marshal.AllocHGlobal(bufferSize); Marshal.StructureToPtr( new SP_DEVICE_INTERFACE_DETAIL_DATA { cbSize = Marshal.SizeOf(typeof(SP_DEVICE_INTERFACE_DETAIL_DATA)) }, detailDataBuffer, false); if (SetupDiGetDeviceInterfaceDetail(hidInfoSet, ref interfaceInfo, detailDataBuffer, bufferSize, ref bufferSize, null))// strtInterfaceData)) { string devicePath = Marshal.PtrToStringAuto(IntPtr.Add(detailDataBuffer, 4)); items.Add(devicePath); } Marshal.FreeHGlobal(detailDataBuffer); index++; } } //删除设备信息并释放内存 SetupDiDestroyDeviceInfoList(hidInfoSet); return items; }
一般会返回好几个文件名，那哪个是你要的呢？方法有二：
1.先获取一次文件名列表，然后插拔或者禁用启用一次Usb设备，变化的那个就是
2.轮流写然后读一次文件名，获取到正确结果的就是
我采用2，然后User.config里面把他记下来。
要读写，首先要打开
（二）打开Usb设备
/// <summary> /// 构造 /// </summary> /// <param name="usbFileName">Usb Device Path</param> public UsbApi(string usbFileName) { if (string.IsNullOrEmpty(usbFileName)) throw new Exception("文件名不能为空"); var fileHandle = CreateFile( usbFileName, GENERIC_READ | GENERIC_WRITE,// | GENERIC_WRITE,//读写，或者一起 FILE_SHARE_READ | FILE_SHARE_WRITE,//共享读写，或者一起 0, OPEN_EXISTING,//必须已经存在 FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, 0); if (fileHandle == IntPtr.Zero || (int)fileHandle == -1) throw new Exception("打开文件失败"); HidD_GetAttributes(fileHandle, out var attributes);// null);// out var aa); HidD_GetPreparsedData(fileHandle, out var preparseData); HidP_GetCaps(preparseData, out var caps); HidD_FreePreparsedData(preparseData); _InputBufferSize = caps.InputReportByteLength; _OutputBufferSize = caps.OutputReportByteLength; _UsbFileStream = new FileStream(new SafeFileHandle(fileHandle, true), FileAccess.ReadWrite, System.Math.Max(caps.OutputReportByteLength, caps.InputReportByteLength), true); }
打开Usb设备我是在构找函数里面完成的，我的类名叫UsbApi。
（三）写
/// <summary> /// 写数据 /// </summary> /// <param name="array"></param> public void Write(byte[] data) { if (_UsbFileStream == null) throw new Exception("Usb设备没有初始化"); if (data.Length > _OutputBufferSize) throw new Exception($"数据太长，超出缓冲区长度({_OutputBufferSize})"); byte[] outBuffer = new byte[_OutputBufferSize]; Array.Copy(data, 0, outBuffer, 1, data.Length); _UsbFileStream.Write(outBuffer, 0, _OutputBufferSize); }
（四）读
/// <summary> /// 同步读 /// </summary> /// <param name="array"></param> public byte[] Read() {
if (_UsbFileStream == null)
throw new Exception("Usb设备没有初始化");
byte[] inBuffer = new byte[_InputBufferSize]; _UsbFileStream.Read(inBuffer, 0, _InputBufferSize); return inBuffer; }
我的Usb设备是半双工的，并且数据只有64字节，所有用了同步读。
（五）关闭
public void Close() { if (_UsbFileStream != null) _UsbFileStream.Close(); }
六、最后
最后写了几行代码测试，巨坑：
1.CreateFile参数的坑
var fileHandle = CreateFile(
usbFileName,
GENERIC_READ | GENERIC_WRITE,// | GENERIC_WRITE,//读写，或者一起
FILE_SHARE_READ | FILE_SHARE_WRITE,//共享读写，或者一起
0,
OPEN_EXISTING,//必须已经存在
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,
0);
这些参数是针对我的Usb设备，各种调整后达到了能读写、能异步。
2.FileStream参数的坑
_UsbFileStream = new FileStream(new SafeFileHandle(fileHandle, true), FileAccess.ReadWrite, System.Math.Max(caps.OutputReportByteLength, caps.InputReportByteLength), true);
缓冲区大小最终采用 System.Math.Max(caps.OutputReportByteLength, caps.InputReportByteLength)
太小读写错误，大点似乎没关系
3.Write的巨坑
public void Write(byte[] data)
这个data长度必须与缓冲区大写一样，而且数据要从data[1]开始写，如你要写“AB”，
var data=new byte[]{0,(byte)'A',(byte)'B'};
事后发现HIDP_CAPS里面的某个值可能告诉我了。
趟了这些坑后，搞定了，能用线程了^-^，发文纪念。
